1. Field of the Invention
This invention relates generally to method and apparatus for detecting ambient air temperature within an electronic device, and, more particularly to a method and apparatus for isolating a temperature sensor from local heating effects of the electronic device.
2. Description of the Related Art
Electronic devices produce heat during operation, and thus, some form of cooling may be required to ensure that they do not overheat during operation. For example, option modules commonly employed in workstations or personal computers are typically constructed from a plurality of discrete and integrated semiconductor devices as well as passive devices, such as resistors, capacitors, and inductors, disposed on a printed circuit board. Each of these devices individually produces at least some heat, and can collectively produce substantial local heating. Typically, heat sinks are positioned in contact with at least some of the heat producing devices, and fans are located on or adjacent the option module to provide substantial air flow over the surface of the devices as well as through the heat sinks. This flow of air is often sufficient to maintain the temperature of the option module within acceptable limits.
To reduce acoustic noise and conserve power consumed by the workstation, it has proven useful to limit the operation of the fan to an as-needed basis. That is, the workstation will operate more quietly and power consumption may be reduced by only operating the fan when additional cooling is required. Typically, a temperature sensor may be deployed on the option module to detect ambient temperature with the workstation, which has proven to be a reliable indicator of the operating temperature of the workstation. That is, operation of the cooling fan may be controlled based on an accurate measurement of the ambient air temperature in the workstation. When the ambient air temperature within the workstation rises above a preselected setpoint, the fan may be turned on to increase cooling airflow within the workstation. Once the ambient air temperature falls below the setpoint, the fan may be turned off to conserve power.
Measuring the ambient air temperature, however, has proven to be somewhat problematic. For example, the temperature sensor is typically located on the option module, and thus, is affected by local heating caused by heat transferred directly through the printed circuit board, rather than by the surrounding air. This local heating may cause the temperature sensor to erroneously sense a falsely high ambient temperature, and cause the cooling fan to operate longer than would otherwise be required. Thus, the local heating reduces the effectiveness of the power savings that could otherwise be achieved.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.